The crystal structure of zeolite NaX (Si:Al ) 1.2) and that of its complex with benzene have been determined at 5 K by Rietveld analysis of powder neutron diffraction data in space group Fd3. For NaX, a ) 25.0328-(5) Å, R wp ) 4.25%, and R p ) 3.27%. For NaX + benzene, a ) 25.0496(7) Å, R wp ) 4.60%, and R p ) 3.52%. The sodium ions were located preferentially in sites SI′ and SII, both of which are fully occupied. The remaining cations were found at the SIII′ site in the 12-ring window. These cations are coordinated by two oxygen atoms, O(1) and O(4), in a corner of the 4-ring window where the aluminum is located. Our simulations on cation positioning in NaX (Si:Al ) 1) predict the preferred occupancy of SIII′ sites that are facing AlO 4 tetrahedra and support our crystallographic results. Less than half the benzene molecules were found at the six-ring window in the supercage, where they interact with the SII cations. No benzene was found in the 12-ring window, presumably because of the presence of the SIII′ sodium cations, but there remains a possibility that undetected benzene is adsorbed near these cations.

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Using Quinolin-65 (Q-65) as a model-adsorbing compound for polar heavy hydrocarbons, the nanosize effect of NiO nanoparticles on the adsorption of Q-65 was investigated. Different-sized NiO nanoparticles with sizes between 5 and 80 nm were prepared by the controlled thermal dehydroxylation of Ni(OH)2. The properties of the nanoparticles were characterized using XRD, BET, FTIR, HRTEM and TGA. The effects of the nanosize on the textural properties, the shape and the morphology were studied. The adsorption of Q-65 molecules onto different-sized nanoparticles was tested in toluene-based solutions. On a normalized surface area basis, the number of Q-65 molecules adsorbed per nm(2) of the NiO surface was the highest for NiO nanoparticles of size 80 nm, while that for 5 nm sized NiO nanoparticles was the lowest. Excitingly, the adsorption capacity of other NiO sizes varied from loading suggesting different adsorption behavior, which exhibits the significance of textural properties during the adsorption of Q-65. Computational modeling of the interaction between the Q-65 molecule and the NiO nanoparticle surface was carried out to get more understanding of its adsorption behavior. A number of factors contributing to the enhanced adsorption capacity of nanoscale NiO were determined. These include surface reactivity, topology, morphology and textural properties.

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